Usually, doctors do not recommend scaling for patients whose oral inflammation has not yet healed, or who suffer from acute infectious diseases, coagulation disorders, and some systemic diseases such as hypertension, heart disease, and diabetes. There are also patients who have serious psychological fear of medical devices, doctors also do not recommend scaling. In addition, other people can be scaled according to their personal situation and according to medical advice.1, acute infectious diseases: such as AIDS, hepatitis B, new crown pneumonia, mumps and other diseases, which can be transmitted through the respiratory tract or blood, and the droplets and blood in the patient’s mouth during the scaling process are more likely to splash out and contaminate the surrounding instruments, ground, and environment, which may transmit infectious diseases to medical personnel and subsequent patients. Therefore, it is not recommended to scaling for such patients; 2. Oral inflammation: If scaling is performed when there is inflammation in the mouth, it is easy to aggravate the inflammation or cause an increase in the scope of inflammation, because scaling will cause gum damage and bleeding, and the inflammation will even spread to the whole body through the blood. This situation is not recommended to scaling, to be healed by inflammation and then scaling; 3, coagulation abnormalities: women during menstruation or suffering from anemia, coagulation dysfunction, thrombocytopenia, diabetes, etc., will reduce the human coagulation function. Normal scaling process, bleeding in the oral cavity is very little and heal quickly, not easy to cause infection, but those with coagulation abnormalities scaling causes a lot of bleeding does not heal, easy to cause oral infection. Doctors do not recommend scaling is generally temporary, after the inflammation in the oral cavity is cured, acute infectious diseases are cured or infectiousness is controlled, the coagulation function returns to normal, the symptoms of hypertension, heart disease and diabetes are relieved, and the patient’s psychological fear is overcome, the normal scaling process can be carried out according to medical advice.